The invention is based on an actuating unit.
An actuating unit of this kind for a wheel brake of a motor vehicle has already been disclosed (DE 195 27 936 A1) in which a variable speed controllable electric motor drives a gear pump, which supplies pressure fluid from a storage tank to a cylinder-piston unit, whose piston can press a brake lining against a friction element connected to a vehicle wheel. On the pressure side, the pump is provided with a throttle, which can control a connection to the storage tank. The pump drive mechanism and the throttle are correspondingly controlled by means of an electronic brake regulation in order to achieve pressure increase, pressure maintenance, and pressure decrease in the cylinder-piston unit.
The actuating unit according to the invention has the advantage over the prior art that on the one hand, in the cooperation of the pump and the element that adjusts the return flow of pressure fluid to the pump, the pressure in the cylinder-piston unit as well as the gradient for pressure increase and pressure decrease can be controlled, but on the other hand, it is also possible to achieve a slip-dependent modulation of the pressure with high dynamics by means of the pressure increase valve and the pressure decrease valve.